What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Allison FOUR

 The ALLISON:FOUR loudspeakers system is of moderate size, the only "bookshelf" system with Stabilized Radiation Loading. It can be put on a table or shelf, or hung on a wall using the wall-mouting hardware supplied.
The system should be placed with its back close to a room wall and with the woofer (mounted in the top panel) facing upward. There should be no object with a large surface area, such as another shelf in a bookcase, closer than 10 to 12 inches above the woofer. When these conditions are met the system power output in the bass range is relatively insensitive to room placement. In uniformity of bass power delivered to a real listening room, the model FOUR's only peers are the larger ALLISON three-way systems.
 The FOUR is a two-way system with a single woofer and two tweeters. But Its extreme low-frequency response is the same as that of the ALLISON:TWO system, and it is the equal of other Allison systems in high-frequency range, smoothness, and omnidirectional dispersion in the forward hemisphere. Therefore it does not "aim" in any direction, and its placement flexibility is practically unlimited. These advantages make it a logical choice wherever floor-standing systems are impractical. And as rear-channel or ambience speakers, FOURs are a splendid alternative to THREEs.

Speaker complement:
One 8" (203 mm) woofers;
Two 1" (25 mm) Convex Diaphragm tweeters
Crossover frequencies:  2 kHz
Crossover network:
LC quarter-section. Air-core tapped choke and polyester capacitors are used. Three-position control switch (accessible from front) supplied for selection of system acoustic power response, from nominally flat to concert-hall balance slope.
Impedance:  8 Ω nominal (6,5 Ω minimum at any setting of balance switch)
Efficiency:  better than 0,7% when placed with back against wall.
Minimum amplifier power:  30 watts per channel to produce 100 dB sound pressure level in most domestic room environments.
Acoustic power output capability: 
0,5 acoustic watt minimum , over full frequency range, with 70 watt peak input.
0,25 acoustic watt minimum in lowest octave, with 35 watts input.
System resonance frequency:  52 Hz, nominal
Effective system Q:  1.0. Low-frequency response -3 dB at 41 Hz, -6 dB at 34,5 Hz, when placed close to center of large wall. Low-frequency output increases when system is placed in typical positions with respect to side wall and floor or ceiling.
Enclosure:  Stabilized Radiation Loading sealed acoustic suspension design.
Outside dimensions:  11" high by 19" wide by 10" front to back (279 mm by 492 mm by 250 mm). Internal volume:  1,265 cubic inches (20,7 liters).
Material:  High density particle board veneered with walnut, oiled finish
Weight:  23,5 lbs (10,7 kg)
Full Waranty for Five Years

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